1. Field of the Invention
This invention relates to novel compounds which prevent or block a FVIIa mediated or associated process or event such as the catalytic conversion of FX to FXa, FVII to FVIIa or FIX to FIXa. In particular aspects, the compounds of the invention bind Factor VIIa (FVIIa), its zymogen Factor VII (FVII) and/or block the association of FVII or FVIIa with a peptide compound of the present invention. The invention also relates to pharmaceutical compositions comprising the novel compounds as well as their use in research, diagnostic, therapeutic, and prophylactic methods.
2. Description of Related Disclosures
Factor VIIa (FVIIa) is a trypsin-like plasma serine protease that participates in hemostasis through the extrinsic pathway of the coagulation cascade (Davie et al., (1991) Biochem. 30(43):10363-10370). FVIIa is converted from its zymogen factor VII (FVII) by proteolysis of a single internal peptide bond. Circulating FVII is a globular protein with an N-terminal γ-carboxyglutamic acid (Gla)-domain, two epidermal growth factor (EGF) domains, and a C-terminal protease domain. Prior to conversion to FVIIa, FVII associates with tissue factor (TF) constitutively expressed on cells separated from plasma by the vascular endothelium (Carson, S. D. and J. P. Brozna, (1993) Blood Coag. Fibrinol. 4:281-292). TF and FVII form a one-to-one protein complex (TF-FVIIa) in the presence of calcium ions (Wildgoose et al., (1993) Biochem. 32:114-119). This association facilitates the proteolysis of FVII to FVIIa at a site (Arg152-Ile153 for human FVII (hFVII)) located between the C-terminal EGF domain (EGF2) and the protease domain (Hagen et al., (1986) Proc. Natl. Acad. Sci USA, 83:2412-2416). While a number of serine proteases activate FVII in vitro, the protease responsible for in vivo activation of FVII is not known (Wildgoose et al., supra).
TF functions as a cofactor for FVIIa with the FVIIa Gla domain interacting at the C-terminal end of TF near the membrane and the FVIIa protease domain situated over the N-terminal domain (Higashi et al., (1994) J. Biol. Chem. 269:18891-18898). The structures of the human TF (hTF) extracellular domain and its complex with active site inhibited FVIIa have recently been determined by x-ray crystallography (Harlos et al., (1994) Nature 370:662-666; Muller et al., (1994) Biochemistry 33:10864; Banner et al., (1996) Nature 380:41-46).
The TF-FVIIa complex constitutes the primary initiator of the extrinsic pathway of blood coagulation (Carson, S. D. and Brozna, J. P., (1993) Blood Coag. Fibrinol. 4:281-292; Davie, E. W. et al., (1991) Biochemistry 30:10363-10370; Rapaport, S. I. and L. V. M. Rao, (1992) Arterioscler. Thromb. 12:1111-1121). The complex initiates the extrinsic pathway by activation of FX to Factor Xa (FXa), FIX to Factor IXa (FIXa), and additional FVII to FVIIa. The action of TF-FVIIa leads ultimately to the conversion of prothrombin to thrombin, which carries out many biological functions (Badimon, L. et al., (1991) Trends Cardiovasc. Med. 1:261-267). Among the most important functions of thrombin is the conversion of fibrinogen to fibrin, which polymerizes to form a clot. The TF-FVIIa complex also participates as a secondary factor in extending the physiological effects of the contact activation system.
The involvement of these plasma protease systems have been suggested to play a significant role in a variety of clinical manifestations including arterial and venous thrombosis, septic shock, adult respiratory distress syndrome (ARDS), disseminated intravascular coagulation (DIC) and various other disease states (Haskel, E. J. et al., (1991) Circulation 84:821-827); Holst, J. et al., (1993) Haemostasis 23 (suppl. 1):112-117; Creasey, A. A. et al., (1993) J. Clin. Invest. 91:2850-2860; see also, Colman R. W. (1989) N. Engl. J. Med 320:1207-1209; Bone, R. C. (1992) Arch. Intern. Med. 152:1381-1389).
Antibodies reactive with the protease domain of FVII have been shown to inhibit TF-FVIIa proteolytic function (Dickinson et al., (1998) J. Mol. Biol. 277:959-971). Peptides corresponding to the EGF2 domain of factor VII are potent inhibitors of TF-FVIIa mediated activation of FX (Husbyn et al., J. Peptide Res. (1997) 50:475-482). Several peptides corresponding to various regions of FVII (for example, amino acid sequence residues 372-337 and 103-112 of hFVII) have been proposed as therapeutic anticoagulants based upon their ability to inhibit TF-FVIIa mediated coagulation (International Publication No. WO 90/03390; International Publication No. WO95/00541). Active site modified FVII variants capable of binding TF have been proposed as pharmaceutical compositions for the prevention of TF/FVIIa mediated coagulation (International Publication No. WO 91/11514). International Publication No: WO 96/40779 describes peptide fragments of TF that inhibit FX activation. U.S. Pat. Nos. 5,759,954, 5,863,893, 5,880,256 and 5,834,244 describes variant Kunitz-type serine protease inhibitors that inhibit TF-FVIIa activity and have been shown to prolong tissue factor initiated prothrombin time (PT). This is consistent with the ability of these TF-FVIIa active site inhibitors to prevent FX activation through inhibition of the TF-FVIIa complex.